The highlight for many is Japanese carmaker Nissan, which showcased self-driving cars that allow the driver to kick back and take their eyes off the road.

A series of sensors constantly monitors the carriageway and objects nearby, turning the wheel automatically to avoid obstacles. "Most accidents are caused by human error," said Nissan in a release.

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Vehicle makers are working to integrate automobiles and houses, with the auto able to power the home -- especially useful in times of blackouts caused by natural disasters.

Honda is showing off a mock installation in which a motorbike powers a gigantic kettle. "Welcome to the future garage that Honda has designed. This is how automobiles and communities will be connected," said Honda president Takanobu Ito.

Many firms have their eyes on the 2020 Tokyo Olympics and the possibilities their technologies could offer by then.

Public broadcaster NHK showed off an ultra high-definition 8K screen, which has around 8,000 pixels on each horizontal line.

"We plan to do experimental broadcasting in 8K by 2016 and we are currently trying our best to be ready to broadcast directly in 8K in 2020", in time for the Tokyo Olympics, said NHK senior engineer Hironori Domen.

"We are displaying 20-inch 4K tablets, which make it possible to integrate what we have seen on paper prints, picture images and movie footage," said Panasonic president Kazuhiro Tsuga. "This is a potential that 4K displays have. Manufacturers will have to widen this potential beyond televisions."

Augmented reality, three-dimensional renderings that seemingly exist in the real world, was a big theme at the fair in Chiba. Pioneer showcased new navigation systems that can direct drivers to vacant parking spots with signs that appear in front of them.

Car electronics maker Clarion has a chatty sat-nav capable of carrying on a conversation with the driver, and reminding him or her to take a break.

"You have driven for a long time. How about a cup of coffee? There is a nice cafe nearby that offers tasty sweets," it says.

The system, powered by Google, also finds restaurants by price bracket, offering suggestions when the driver tells it: "I would like a place where I can have lunch for 1,000 yen ($10)."

NTT Docomo demonstrated augmented reality spectacles that can translate a menu in real time. Its latest development combines cameras, computers and know-how to give the wearer a different view of what they are looking at.

One function of the gadget overlays the wearer's first language onto unfamiliar text, making signs and menus instantly understandable -- a boon to travellers in Japan, where foreign-language menus are not commonly found off the tourist trail.

"Character-recognition technology enables instant language translation for users travelling abroad and reading restaurant menus and other documents," Docomo said in a statement.

Another application turns any flat surface into a touchscreen, with a finger ring relaying positioning information to the device that lets wearers "touch" tags that only they can see, perhaps to perform an Internet search.

NTT Docomo said a user wearing the glasses and ring set could dispense with the need to carry a laptop or a tablet.

Other uses include facial recognition that could look up someone's identity -- and job title -- from a smartphone's directory.

More than 580 companies are taking part in the trade show, which has brought exhibitors from 18 countries and territories. The show runs until Saturday.